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Biomedical subjects

L Foster

Publications and source records attributed to L Foster.

At least 55 records · Page 3Linked to original sources
PubMed1990

Resistance to H-2-restricted but not to allo-H2-specific graft and cytotoxic T lymphocyte responses in lymphoma mutant.

The lymphoma mutant RMA-S escaped graft rejection after transplantation over a minor histocompatibility barrier, whereas it was rejected in H-2 allogeneic mice. The parental control line was rejected in both situations. The mutant, which had been selected against MHC class I molecules retained 5 to 10% of the wild-type H-2Db, Kb, and beta 2-microglobulin expression on the cell surface. It remained sensitive to allo-H-2b CTL in vitro, but was completely resistant to minor histocompatibility antigen-specific, H-2b-restricted CTL. It was equally resistant to other H-2b-restricted responses against internally derived Ag, such as tumor-specific CTL or a CTL clone specific for the influenza virus nucleoprotein. The results indicate a target cell defect that selectively abolishes the sensitivity to H-2-restricted CTL directed against internally processed Ag. This appears sufficient to shift the transplantation response over a minor histocompatibility Ag barrier from rejection to acceptance. There are two possible explanations for the results: 1) a block in the MHC class I-directed pathway for internal Ag processing, and 2) subthreshold H-2/Ag ligand density in relation to triggering requirements of restricted CTL. Regardless of the type of defect, the results demonstrate a difference between allo-H-2-specific and H-2-restricted CTL recognition at the level of the target cell.

Cytotoxicity, Immunologic↗
PubMed1990

Antischistosomal action of mevinolin: evidence that 3-hydroxy-methylglutaryl-coenzyme a reductase activity in Schistosoma mansoni is vital for parasite survival.

The enzyme 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA reductase) plays an important role in regulating egg production in the human parasitic trematode Schistosoma mansoni. Infected mice treated with a low dose of mevinolin, an inhibitor of this enzyme, stopped egg production by the parasite and blocked the pathology associated with the infection. As an extension of this work, we exposed adult and developing schistosomes to higher doses of mevinolin for an extended period of time and observed the following: administration of 0.2% mevinolin in the diet of infected mice for 14 days resulted in 96-100% elimination of adult parasites. Administration of the same dose for 2 days before, and for 15 days after infection, resulted in 93-96% reduction of adult parasites. Co-administration of mevinolin with 0.5% mevalonate, but not 0.5% cholesterol, blocked the antischistosomal activity of mevinolin. We monitored schistosomal and mouse liver HMG-CoA reductase activity during the course of treatment and observed that HMG-CoA reductase activity was elevated in the liver but significantly reduced in the parasite. In vitro incubation of paired schistosomes with mevinolin, for up to 11 days, resulted in a dose- and time-dependent reduction of parasite motility and lactate production with eventual death. These in vitro effects were no evident when mevalonate was added to the culture system in place of, or in addition to, mevinolin. Collectively, the evidence suggests that mevalonate and/or metabolite not only plays a vital role in schistosome egg production, but is vital for survival of the parasite.

Animals↗
PubMed1990

Cloning and expression of a membrane antigen of Entamoeba histolytica possessing multiple tandem repeats.

Entamoeba histolytica causes amebic dysentery and amebic liver abscess, major causes of morbidity and mortality worldwide. We have used differential hybridization screening to isolate an E. histolytica-specific cDNA clone. The cDNA was found to encode a serine-rich E. histolytica protein (SREHP) containing multiple tandem repeats. The structural motif of SREHP resembles some of the repetitive antigens of malarial species, especially the circumsporozoite proteins. A recombinant trpE fusion protein containing the tandem repeats of SREHP was recognized by immune serum from a patient with amebiasis, demonstrating that SREHP is a naturally immunogenic protein. An antiserum raised against the recombinant fusion protein specifically bound to two distinct bands with apparent molecular masses of 46 and 52 kDa in a crude preparation of E. histolytica trophozoite membranes. This antiserum also inhibited E. histolytica trophozoite adhesion to Chinese hamster ovary cells in vitro. The ability to isolate E. histolytica-specific genes, and to express those genes in Escherichia coli, may be important in studying the molecular basis of E. histolytica pathogenesis and for the future development of vaccines.

Amino Acid Sequence↗
PubMed1989

Association of class I major histocompatibility heavy and light chains induced by viral peptides.

We describe a cell in which association of a major histocompatibility complex class I heavy chain with beta 2-microglobulin is induced by a peptide derived from influenza nucleoprotein. Association of antigenic peptides with the binding site of class I molecules may be required for correct folding of the heavy chain, association with beta 2-microglobulin and transport of the antigen-MHC complex to the cell surface.

Animals↗
PubMed1989

A mutant cell in which association of class I heavy and light chains is induced by viral peptides.

Association of the Db heavy chain with beta 2-microglobulin and expression of Db and Kb at the surface of the cell are induced by specific peptides in the mutant RMA-S. Association of antigenic peptides with the binding site of class I molecules may be required for correct folding of the heavy chain, association with beta 2-microglobulin, and transport of the antigen-MHC complex to the cell surface.

Amino Acid Sequence↗
PubMed1987

Molecular mapping of class II polymorphisms in the human major histocompatibility complex. I. DR beta.

We have studied 27 cell lines homozygous by consanguinity for the major histocompatibility complex to establish the restriction fragment length polymorphism (RFLP) patterns seen with six different restriction enzymes (Bam HI, Bg1 II, Eco RI, Hinc II, Hind III, Pvu II) and DR beta chain probes. The probes used were a full-length cDNA DR beta probe and a probe specific for the 3' untranslated region. The RFLP obtained represent the first standard patterns for the individual haplotypes DR1 through 7 and DR9 as defined by genetically homozygous lines. The patterns obtained reflect the DR specificities closely, as well as the DRw52 and DRw53 specificities. These latter specificities are associated with the most prominent patterns of RFLP. Bands are present which are unique for the haplotypes DR1, DR2, DR4, DR7, DRw52, and DRw53, and could be used for typing these haplotypes in heterozygotes. Subtypes can be identified for all of the haplotypes except DR1. These subtypes indicate that there is an extensive amount of polymorphism in the DR subregion that has not been identified serologically.

Cell Line↗
PubMed1987

Allelic variation in the DR subregion of the human major histocompatibility complex.

Allelic variation in the DR subregion of the human major histocompatibility complex has been analyzed by nucleic acid sequencing of cDNA clones obtained from cell lines homozygous by consanguinity for all the common serological types DR1-9. Two expressed loci were identified in the haplotypes DR2, -3, -4, -7, and -9; one locus being present at a much lower frequency (4-7%) than the other. The low-frequency allele was highly conserved between each of the DRw53 (DR4, -7, -9) and the DRw52 (DR3, -5, -6) haplotypes. Analysis of the variation between alleles confirms the presence of three allelic hypervariable regions. At each variable residue, a limited range of amino acid substitutions are found, distinguishing them from immunoglobulin hypervariable regions. Dinucleotide substitutions are extremely common. Individual hypervariable regions are often shared between haplotypes. Much of the variation in these alleles can be attributed to the shuffling of these regions between haplotypes, possibly by the mechanism of gene conversion.

Alleles↗
PubMed1986

A population-based study of hemolytic-uremic syndrome in Oregon, 1979-1982.

The authors conducted a retrospective hospital-based chart review of cases of hemolytic-uremic syndrome among children less than or equal to 18 years of age, hospitalized in Oregon during the four-year period from January 1979 to December 1982. Thirty children with hemolytic-uremic syndrome living in Oregon were hospitalized during this period, for an average annual incidence of 0.97 cases per 100,000 children. Seventy per cent of cases occurred in children under five years of age, for an incidence of 2.65 cases per 100,000 children. Twenty-seven (90%) of the 30 children were white, and 17 (57%) were female. Twenty-four (80%) had a diarrheal prodromal illness including 20 who had bloody diarrhea. Twelve children (40%) acutely required peritoneal dialysis, and two (7%) developed chronic renal failure. Three children died, for a case fatality ratio of 10%. Sixty per cent of the 30 cases occurred during the summer and early fall months. Geographic clustering was also evident. Hemolytic-uremic syndrome is a rare but endemic disease in Oregon and may occur in small clusters. Although descriptions of several large series of patients have been published, this study describes the first statewide population-based study of this syndrome.

Adolescent↗
PubMed1986

Immediate public health concerns and actions in volcanic eruptions: lessons from the Mount St. Helens eruptions, May 18-October 18, 1980.

A comprehensive epidemiological evaluation of mortality and short-term morbidity associated with explosive volcanic activity was carried out by the Centers for Disease Control in collaboration with affected state and local health departments, clinicians, and private institutions. Following the May 18, 1980 eruption of Mount St. Helens, a series of public health actions were rapidly instituted to develop accurate information about volcanic hazards and to recommend methods for prevention or control of adverse effects on safety and health. These public health actions included: establishing a system of active surveillance of cause-specific emergency room (ER) visits and hospital admissions in affected and unaffected communities for comparison; assessing the causes of death and factors associated with survival or death among persons located near the crater; analyzing the mineralogy and toxicology of sedimented ash and the airborne concentration of resuspended dusts; investigating reported excesses of ash-related adverse respiratory effects by epidemiological methods such as cross-sectional and case-control studies; and controlling rumors and disseminating accurate, timely information about volcanic hazards and recommended preventive or control measures by means of press briefings and health bulletins. Surveillance and observational studies indicated that: excess in morbidity were limited to transient increases in ER visits and hospital admissions for traumatic injuries and respiratory problems (but not for communicable disease or mental health problems) which were associated in time, place, and person with exposures to volcanic ash; excessive mortality due to suffocation (76 per cent), thermal injuries (12 per cent), or trauma (12 per cent) by ash and other volcanic hazards was directly proportional to the degree of environmental damage--that is, it was more pronounced among those persons (48/65, or about 74 per cent) who, at the time of the eruption, were residing, camping, or sightseeing (despite restrictions) or working (with permission) closer to the crater in areas affected by the explosive blast, pyroclastic and mud flows, and heavy ashfall; and de novo appearance of ash-related asthma was not observed, but transient excesses in adverse respiratory effects occurred in two high-risk groups--hypersusceptibles (with preexisting asthma or chronic bronchitis) and heavily exposed workers. Laboratory and field studies indicated that: volcanic ash had mild to moderate fibrogenic potential, consisting of greater than 90 per cent (by count) respirable size particles which contained 4-7 per cent (by weight) crystalline free silica (SiO2).(ABSTRACT TRUNCATED AT 400 WORDS)

Air↗
PubMed1984

The EB virus genome in Daudi Burkitt's lymphoma cells has a deletion similar to that observed in a non-transforming strain (P3HR-1) of the virus.

Epstein-Barr virus (EBV) DNA isolated from the frequently studied and unusual Burkitt's lymphoma cell line, Daudi, contains a 7.4-kb deletion, similar to (but larger than) that found in a non-transforming isolate of the virus, P3HR-1. A comparison of EBV sequence in Daudi cells with that from a comparable region in a wild-type, transforming strain of the virus (B95-8) indicates that at least two of the previously identified RNAs, a highly repetitive sequence, and other interesting coding or structural features should be absent in Daudi EBV DNA as a consequence of the deletion. The information removed by the deletion, as well as that which might be generated by juxtaposition of two regions of the genome that are not adjacent in most strains of the virus are discussed.

Base Sequence↗
PubMed1982

In vitro synthesis of type IV procollagen.

Total RNA was isolated from parietal endoderm cells of 131/2-day mouse embryos that synthesize large amounts of type IV procollagen. In vitro translation of this RNA in the reticulocyte lysate supplemented with a ribonuclease inhibitor yielded two equally prominent polypeptides of Mr = 165,000 and 168,000, immunoprecipitable with anti-mouse type IV collagen serum. The Mr = 165,000 polypeptide was shown by one-dimensional peptide mapping to represent an unmodified chain of type IV procollagen. The Mr = 168,000 polypeptide, the in vitro synthesis of which was barely detectable in the absence of a ribonuclease inhibitor, most likely represents the other genetically distinct chain of type IV procollagen. Similar results to those described were also obtained using poly(A) + RNA prepared from murine F9 embryonal carcinoma cells induced to differentiate in vitro into parietal endoderm.

Animals↗
PubMed1981

Postnatal maturation of gonadotropes in the male rat pituitary.

The postnatal maturation of gonadotropes was studied with the use of electron microscopic-immunocytochemical strains for the beta-chains of LH and FSH on serially sectioned fields. A third serially sectioned field was stained with antiserum to ACTH-(17-39). Morphometric studies on semithin and ultrathin plastic sections stained for LH and FSH showed a 200-300% increase in the percentages of LH and FSH cells during the first week of postnatal life. In the 1- to 2-week-old rats, the percentage of gonadotropes in the population was greater than that in the adult. Analysis of the hormone content of serially sectioned gonadotropes showed that storage patterns similar to those in the adult were reached by the seventh day of life. In the neonatal group, 66% of the serially sectioned cells contained both FSH and LH, 20% contained only LH, and 14% contained only FSH. In the 7- to 15-day-old rats, the percentages of gonadotropes containing both hormones increased to 79% while 10-11% of the cells contained only LH or FSH. This is similar to the findings in the adult rat population (75% LH and FSH cells, 14.2% LH cells, and 11% FSH cells). The fields stained for ACTH showed that 35-80% of the gonadotropes contained ACTH-like immunoreactivity during neonatal development, with the highest values seen in the 7- to 15-day-old rats. In the normal adult rats, 2-10% of the gonadotropes contain ACTH activity. Cells containing only ACTH were also seen in all age groups examined. The morphological analysis showed that immature gonadotropic cells contained scattered storage granules, arranged either at the cell periphery or concentrated near the nucleus. They were small, irregularly shaped, and often exhibited a high nucleo-cytoplasmic ratio. They were difficult to distinguish from corticotropes. More mature cell types were found after 1 week of age. These were ovoid and contained numerous large and small granules, features similar to the adult type I cell. The granules, however, were more irregularly shaped (pleomorphic). Immature forms were observed in the gonadotrope population as late as 15 days of age. Most gonadotropes from the 20- to 25-day-old rats resembled those in the adult population. Our findings support the physiological studies which show that the first week of life is an important time for functional and morphological maturation of the gonadotrope population. They also support the finding that immature gonadotropes are larger, more numerous, and more heterogeneous than those in the adult male rat population. Finally, we propose that a subpopulation of gonadotropes may serve as a stem cell or may be involved in the development of adrenal-gonadal interactions.

Adrenocorticotropic Hormone↗
PubMed1981

Nonspecific local immune inhibition of herpes simplex virus keratitis.

Rabbit cornea, which had recovered from initial sensitization to bovine serum albumin were found to possess immune memory capable of responding to a totally different antigenic stimulus, i.e., viable herpes simplex virus. Two months after BSA sensitization these corneas were found to be extremely resistant to primary infection by the virus. The long term residence of mononuclear leukocytes in the cornea, following BSA sensitization, is apparently responsible for this non-specific immune phenomenon.

Animals↗
PubMed1978

Thyroid function tests in elderly hyperthyroid patients.

Several tests of thyroid function were performed in 35 hyperthyroid patients over the age of 65 (elderly). The results were compared to those of similar tests in 48 hyperthyroid patients under the age of 65 (young). Total serum thyroxine (T4) was within the normal range in 14 percent of the elderly and 11 percent of the young hyperthyroid patients. The free thyroxine index (FTI) was within the normal range in 11 percent of both groups. The triiodothyronine uptake (T3U) proved to be a poor test in both groups. Although elevation of the triiodothyronine (T3) level allowed a diagnosis of "T3-toxicosis" in 2 elderly and 3 young hyperthyroid patients, the T3 level was normal in 34 percent of the elderly and 13 percent of the young subjects. Correction of the T3 range for age reduced the number of normal T3 values to 12.5 percent in the elderly hyperthyroid patients. The 24-hour uptake of radioactive iodine was normal in 12 percent of the young hyperthyroid patients, 27 percent of the elderly patients with Graves' disease, and 70 percent of the elderly patients with toxic nodular goiter, despite recent readjustment of the normal range for the test. It is concluded that the diagnosis of hyperthyroidism in the elderly may be difficult and that no single test can be relied upon to exclude the diagnosis.

Adult↗
PubMed1975

Carcinoembryonic antigen-positive metastatic adenocarcinoma of the choroid. A case report.

Plasma carcinoembryonic antigen (CEA) levels were found to be elevated in a 62-year-old woman who came to us with a diffuse choroidal mass in the left eye. Although a metastatic tumor was suspected clinically, a thorough medical evaluation failed to detect a primary lesion and the eye was enucleated. The histologic diagnosis was metastatic adenocarcinoma. On immunohistologic assay, the choridal metastases stained positively for CEA. We believe this to be the first CEA-positive intraocular tumor to be reported.

Adenocarcinoma↗